Apparatus and method for adjusting a feed-forward signal for seek control during a seek operation

1. A hard disk drive control module comprising:

a feed-forward signal input port communicatively coupled with a reference model;

a tracking error signal input port communicatively coupled with a magnetic transducer of said hard disk drive;

an error calculator module configured for determining a difference between an estimated tracking error signal in response to a first feed-forward signal and an actual tracking error signal of said magnetic transducer in response to said first feed-forward signal, said error calculator comprising:

a feed-forward signal double integrator configured for double integrating and filtering said first feed-forward signal during seeking and settling of a magnetic transducer, resulting in an estimated position of said magnetic transducer;

a gain difference calculator configured for calculating a gain error from said double integrated and filtered first feed-forward signal, after seeking and settling of said magnetic transducer are completed based on said first feed-forward signal; and

a phase difference calculator configured for calculating a phase error from said double integrated and filtered first feed-forward signal, after seeking and settling of said magnetic transducer are completed based on said first feed-forward signal;

a feed-forward signal adjuster module configured for adjusting a gain and a phase for a second feed-forward signal based on said difference between said estimated tracking error signal in response to said first feed-forward signal and said actual tracking error signal of said magnetic transducer;

a feed-forward signal adjustment output port communicatively coupled to said second feed-forward signal;

an error comparator configured for comparing said gain error and said phase error from said double integrated and filtered first feed-forward signal, to an estimated tracking error waveform due to gain error and an estimated tracking error waveform due to phase error;

a gain summation node configured for adding said gain error to a gain of said second feed-forward signal, based on a comparison performed by said error comparator; and

a phase summation node configured for adding said phase error to a phase of said second feed-forward signal, based on a comparison performed by said error comparator.

2. The hard disk drive control module of claim 1 wherein said gain difference calculator configured for calculating a gain error comprises:

a filter configured for estimating a tracking error waveform due to said gain error from said double integrated and filtered first feed-forward signal based on said first feed-forward signal.

3. The hard disk drive control module of claim 1 wherein said phase difference calculator configured for calculating a phase error comprises:

a filter configured estimating a tracking error waveform due to said phase error from said double integrated and filtered first feed-forward signal based on said first feed-forward signal.

4. The hard disk drive control module of claim 1 wherein said error comparator comprises:

an estimated tracking error waveform receiver; and

an actual tracking error waveform receiver.

5. The hard disk drive control module of claim 1 wherein said error comparator further comprises:

a correlation calculator configured for calculating a correlation between an actual tracking error signal and an estimated tracking error waveform.

6. A method for adjusting a feed-forward signal during a seek operation, said feed-forward signal enabling a voice coil motor to position a magnetic transducer upon a data track, said method comprising:

receiving a first feed-forward signal from a reference model associated with a location of said data track;

receiving a tracking error signal derived from a position error signal from a magnetic transducer coupled to said slider;

seeking said data track with said voice coil motor and said slider based on said first feed-forward signal;

calculating a phase difference of said reference model from an actual value which is indicated by said tracking error signal, and an estimated tracking error signal derived from said first feed-forward signal received from said reference model; and

adding said phase difference to a second feed-forward signal;

double integrating and filtering said first feed-forward signal during seeking and settling of said voice coil motor and said slider;

filtering said first feed-forward signal;

calculating a phase difference and a gain difference from said double integrated and filtered first feed-forward signal after said seeking and said settling of said magnetic transducer are completed in response to said first feed-forward signal;

comparing said phase difference and said gain difference; and

adding said phase difference and said gain difference to a respective gain and phase of said second feed-forward signal based upon said comparing.

7. The method as recited in claim 6 , wherein said calculating a phase difference and a gain difference comprising:

comparing an estimated tracking error of said magnetic transducer to an actual tracking error of said magnetic transducer comprising;

double integrating and filtering said first feed-forward signal to determine an estimated tracking error from said reference model; and

determining said phase difference and said gain difference between said actual tracking error signal waveform, which is based on said feed-forward signal, and said estimated tracking error signal waveform, which is based on said reference model.

8. The method as recited in claim 6 , wherein said calculating a phase difference and a gain difference comprising:

calculating a correlation between an actual tracking error waveform and an estimated tracking error waveform.

9. The method as recited in claim 6 , wherein said adding said phase difference and said gain difference to a second feed-forward signal comprising:

adding a null value to said second feed-forward signal when said correlation presents no similarity between said actual tracking error waveform and said estimated tracking error waveform.

10. The method as recited in claim 6 , wherein said adding said phase difference and said gain difference to a second feed-forward signal comprising:

adding a negative value to said second feed-forward signal when said correlation between said actual tracking error waveform and said estimated tracking error waveform is positive.

11. The method as recited in claim 6 , wherein said adding said phase difference and said gain difference to a second feed-forward signal comprising:

adding a positive value to said second feed-forward signal when said correlation between said estimated tracking error waveform and said actual tracking error waveform is negative.